Thread-controlling mechanism for sewing machines



Aug. 14. 1928.

R. BECKER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Feb. 4, 1926 4 Sheets-Sheet l INVENTOR ATTORNEY Aug. 14, 1928.

Filed Feb. 1926 4 Sheets-Sheet 2 NVENTOR ATT RNEY WlTNESESaVPK' yWM Aug. 14, 1928.

R. BECKER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Feb. 1926 4 Sheets-Sheet 3 WITH ESSES ATTORNEY Aug. 14, 1928.-

ATTORNEY R. BECKER THREAD CONTROLLING MECHANISM FOR SEWING MACHINES Filed Feb. 4, 1926 '4 Sheets-Sheet 4 Patented Aug. 14, 1928.

UNITED STATES PATENT OFFICE.

RUDOLPH BECKER; OE PLAINFIELD, NEW JERSEY,ASSIGNOR TO THE SINGER MANU- FACTUBING COMPANY, OF ELIZABETH, NEW JERSEY, A CORPORATION OF NEW JERSEY.

THREAD-CONTROLLING MECHANISM FOR SEWING MACHINES.

A Application filed February 4, 1926. Serial No-. 85,842.

This invention relates to thread-controlling mechanism for sewing machines and has for an object to improve the mechanism disclosed in my Patent No. 1,386,307, of August 2, 1921. In the mechanism disclosed in said patent there is embodied a thread-nipper device comprising an. adj ust'able nipper-seat connected to the feed-adjusting means, and a nipper-head which is actuated by means of an eccentric on the main-shaft. With this device, an adjustment of the feed or stitch length alters the timing of both the beginning and ending of the nip, whereas for best results the timing of the ending of the nip should be the same for all stitch lengths, for at this time the eyed and hooked needles are emerging from the upper side of the work and the thread should be allowed to run free- 1y from the supply as the needles move to the upper limit of their stroke. It has been proposed (see U. S. Patent No. 392,087) to utilize a barrel cam for actuating the threadnipper, said cam having a ledge or step parallel to its axis to effect. the release of the thread at a fixed time and an obliquely or spirally formed let-01f portion to effect the nipping of the. thread at a time dependent upon the stitch-length adjustment, such adjustment effecting a shift of the cam lengthwise of the cams axis so that the let-off portion will be engaged earlier or later by the cam-follower. A cam mechanism of this character is, however, rather bulky and complicated and requires considerable space within the machine for its installation and operation.

An object of the present invention is to provide a nipper-operating mechanism of compact and simpli ed construction retaining the desirable characteristics of a variable beginning and a fixed ending of the time of the nipping action.

A further object of the invention is to provide for proper tensioning of the thread when sewing with stitches of short or medium length while permitting the thread to run more freely when sewing longer stitches. To this end there is provided a thread-nipper having co-acting members one of which a (the nipper-seat) is adjustable and the other of which (the nipper-head) is connected to a cam-follower cooperatively related to a cam fixed on the machine shaft and formed with a. graduated eccentric let-ofi portion allowing the nipper-head to approach the nipper-seat over a certain portion or fraction of the stitch-forming cycle; the time at which the nip actually occurs depending upon the position of adjustment of the seat toward or away from the nipper-head. The cam also is formed with an abrupt cam-rise following the graduated eccentric or let-oii portion and equal to the total drop ofsueh let-off portion to effect the release of the thread at a fixed period of the stitch-forming cycle for all stitch-lengths at about the time when the eye of the eyed needle is doubling its thread through the work.

A thread tension device is also used in addition to the thread-flipper and the adjusting means for varying thetiming of the thread-nipper is connected to open the tension device when the nipp er is adjusted for sewing long stitches. y

In the accompanying drawing, Fig. 1 is a side elevation of a sewing machine embodying the invention. Fig. 2 is a horizontal section through the bracket-arm standard of the machine, showing the. bed in plan. Fig. 3 is a front end elevation ofthe machinebcd. Fig. 4 is a sectional view on the line 44, Fig. 2. Fig. 5 is a sectional view on the line 55, Fig. 1. Fig. 6 is an inside elevation of the nipper-adjusting lever and Figs. 7, 8 and 9 are, respectively, diagrammatic views illustrating the variation in the timing of the beginning point of the nip for short, intermediate and long stitches.

.The invention is disclosed as embodied in a. strawbraid sewing machine having the usual eye-pointed needle 1 and hook needle 2 actuatcd by suitable mechanism such as that disclosed in my Patent No. 1,429,399, of Sept. 19,1922, which also discloses a suitable iorm of presser-foot and looper mechanism. The feeding mechanism comprises a feed-dog 3 which is carried by the feed-bar 4i fulcrumed at 5 on the feed-rocker 6. Rising and falling movements are imparted to the ieedbar by means of the feed-lift eccentric 7 on the main-shaft 8. The feed-lift eccentric actuates the pitman 9 which raises and lowers the support 10 for the link 11 pivoted at 12 to the feed-bar 4; this mechanism being constructedsubstantially in ac* cordance withthe disclosure of my said patent. Feed-and-return movements. are im parted to the iced-rocker 6 by means of the forked pitman 13 which embraces the cam 14 on the n'iain-sha'lt and has a link connection 15 with an arm 16 on the fced-adjusting lever which is fulcrumcd at 17; the other arm 18 of the feed-adjusting lever projecting- .exteriorly oi the-machine bed and carrying a spring-pressed latch-member 19 having a toothed end 20 adapted to engage a selected one of a series of depressions iirtbe statioiv ary rack-member 22. Fulcrumed at 23 on the head 18' of the lever-M11118 is a lever 24 having-a cam edge 25 which forces the latchmcmber 19 outwardly'to disengage the tooth 20 from the rack 92 preliminary to swinging the lever 18 for adjustment of the stitchlength.

An under-thread take-up. lever 26 isl ulerumed at 27 on the machine frame and is formed at its free end with a thread-eye 28. This .lever 26 is actuated by means of the linleconnection 29 with the pitman 9.

The machine is provided with a threadeontrolling device including spaced threadeyes 30 between which plays the aperturcd end 31 of a threadcontrolling lever 32 fulcrumed on the main-shaft 8 and having its rearwardly extending arm 33 formed with an armiate cam-slot 34 which is engaged by a pin .35 secured to the pitman 13 by the screw-andsslot.adjustable fastening 36 per mitting adjustment of the pin longitudinally of the guideway 37 on the pitman 13.

The intermittent thread-nipping device comprises coacting nipper'seat and nipperhead members 38 and 39 respectively. The nipper-seat member 38 is an apertured cylindrical member which is fixed within the cylindrical casing 40 rotatably and slidably fitted to an aperture in the frame wall 41 of the machine bed. The member 40, Fig. 2, has an inclined slot 42 cut in its wall and this slot isentered by a screw 43 whereby a turning movement imparted to the casing 40 will causesuch casing and the nipper-seat 38 to move in and ,out in an axial direction g1 toward and away from the nipper-head The casing 40 has fixed thereto, F ig. 6,

the lever 44 one armof which is forked at 45 to embrace the feed-adjusting lever arm 18/ The other arm of the lever 44 has an inclined end 46 serving as a releasing cam for the tension device 47. Referring to Fig. 5 it will be observed that the constant or non-intermittent tension device includes the usual thread-engaging disks 48 and adjustable tension spring 49 the pressure of which on the disks may be entirely relieved by an outward thrust on the tension-releasing pin 50; such thrust being caused by the cam end 46 of the lever 44 when the feed-adjusting mechanism is adjusted to sew long stitches.

The nipper-he'ad 39, Fig. 4, is carried by a shank 51 passing axially through the 0y lmclrical nipper-seat and having secured to its inner end the cam-followm' roll A spring 53 housed within the nippcr-seat cylinder 38 tends to draw the head 39 into effective nipping relation with the seat 38.

To hold the nipper open and penrnit it .to close at .PIGClGtGl'lTlillQEl interva s of a stitch-forming cycle there is iixedyto the main-shaft- Sa cam 54 having an abrupt nipper opening lllCllllO55 followed by a concentric portion to the beginning point 50 of a graduated eccentric let-oll' portion ending at 57, such let-oli' portion extending over some 120 or more of the cams extent, as shown by the dotted radial lines, Fig. 4-. It will be observed. that in the embodiment illustrated the let-oil portion embraced within the radial dotted lines is graduated into three let-oii' steps 5b and .56, i. 0., is a stepped eccentric .curve, and it has been found that a. suliiciently accurate tuning of thcclosul'e ofthe nipper for all stitch-length adjustments is produced by. a three-step graduated nipper-closing cam-portion.

Referring to Fig. 7, the feed being adjusted for short stitches, the nippcr-seat occupies a position so near to the nipper-bead 39 that the let oii' portion 56" oi the cam permits the nipper-head to nip the thread against the nipper-seat as the needles are nearing theendof their down stroke. With a short stitch the thread is. slack at this time and the SllbSOqlllEllt action of the take up 26 and threa(lcontroller 32 controlsthe slack-thread until the rising eye-pointed needle has safely entered the loop carried by the hook-needle.

When sewing stitches of intermediate length, Fig. 8, the'time ofthe nip shouldbe delayed to permit more thread to be drawn into the stitch and such delay is effected by virtue of the-intemnediate positioning of the nipper-seat by its connection with the feedadjusting mechanism. When the nipperseat occupies intermediate position it is not near enough to the nipper-head to nip the .thread when the roller 52 rides on the first let-off step 56 but does nip the thread when the roller rides onto the second let-off step 56". After the thread is nip 16d, the downwardly moving take-up 26 he ds the threadloop snugly in the barb of the rising hook needle until the eye-pointed needle has safely entered such loop. I

When sewing long stitches, Fig. .9, thgnjp is delayed until the needles are entering the work. "The long stitch-adjustment of the feed, shifts-the nipper-seat so far away from the nipper-ihead that the two do not come 1n'to effective nipping relationshi :untilsthe roller rides onto the third let-o :step 56. It will be seen that the a present variably t med nipper mechanism is ofcoin act and simple construction and requires at little space within the machine bed for its im 7 stallation.

Having thus set forth the nature of the invention, what I claim herein is 1. In a thread-nipper mechanism for sewing machines, the combination with coacting thread-nipping members, one of which is active and the other of which is adjustable toward and away from the active member, of an operating cam for actuating the active nipper member having a graduated eccentric nipper-closing portion and an abrupt nipper-opening portion.

2. In a thread-nipper mechanism for sewing machines, the combination With a nipperhead anda nipper-seat adjustable toward and away from the nipper-head, of a nippen head operating cam having agraduated eccentric nipper-closing portion followed by an abrupt nipper-opening step substantially equal to the total drop of said graduated nipper-closing portion.

3. In a thread-flipper mechanism, a framesupport, a shaft, a nipper-operating cam fixed to said shaft, a cylindrical nipper-seat mounted in said frame for axial adjustment transversely of said shaft, a nipper-head opposed to said seat, a shank carrying said nipper-head and passing through said seat, a cam-follower carried by said shank in cooperative relation with said cam, said cam having a graduated eccentric let-off portion followed'by an abrupt nipper-opening step substantially equal to the total drop of said let-ofi portion.

4. In a sewing machine, the combination with feed-adjusting mechanism, of a threadnipping device including coacting nipping elements, means connected to the feed-adjusting mechanism for shifting one of said elements toward or away from the other, and means for actuating the other nipping element, said means including a cam having aradially graduated 'nipper-closing portion followed by an abrupt nipper-opening portion.

5. In a straw sewing machine, the combination with stitch forming mechanism ineluding side-by-side eye and hook needles and feed-adjusting mechanism, of a con- I stant tension device, and means connected to the feed-adpistmg mechanism for entirely opening the tension device when the feed-' adjusting mechanism'is set for the production of the longer stitches.

6. In a sewing machine, the combination with feed-adjusting mechanism, of an inter-' mittent thread-nipping device and a constant tcnslon 'dBVlCG, and means connected to the feed-adjusting mechanism forvarying the time of action of the thread-nipping device in accordance with the stitch-length adjustment and for opening the tension device for a long-stitch adjustment.

In testimony whereof, I have signed my name to this specification.

RUDOLPH BECKER. 

